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| Vol. 22, No. 12 |
| July 1, 2000 |
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Telling Time by FRAN DRESSMAN Harris County Psychiatric Center "Time, time, time... See what's become of me . . . ." Simon and Garfunkle's lyrics have special meaning for the middle-aged American population of Baby Boomers who will soon be entering the nation's fastest-growing population group, the elderly. The average life expectancy for Americans is 76 years. There are now 33 million Americans over age 65 and they account for 12.5 percent of the population, a figure that is predicted to grow to almost 20 percent by the year 2030. Currently, there are approximately 260,000 adults over 65 in Houston. The lyrics also have special meaning for Drs. Nelson Gruber and Roy Varner, Harris County Psychiatric Center (HCPC) psychiatrists who were principal investigators in a research effort studying the effectiveness of clock drawing tests to assess for cognitive (pertaining to mental processes, e.g., thinking, reasoning, etc.) impairment in geriatric psychiatric patients. Dr. Gruber, attending physician on HCPC's geriatric psychiatry unit, was the lead author of an article on a collaborative research venture which included Dr. Varner, HCPC's medical director; former UT-Houston Mental Science Institute (MSI) research psychologist Dr. Yuan-Who Chen; and Dr. Jary Lesser, director of the MSI Geriatric Clinic. All are faculty members in the department of psychiatry and behavioral sciences of the UT-Houston Medical School. "Aging," reminds Dr. Varner, "is not pathological. It's a natural part of life, independent from the process of disease; all living things age." And measurable aging, which usually begins around age 30, affects all parts of the human physiology. "After maturation," Dr. Varner says, "all body organ systems start to decline functionally. As we age, there is a reduction in the amount of total body water, a loss of calcification in the bones, a decrease in striated muscle mass and an increase in fat, a decline in the resting cardiac output and a blunting of the ability to metabolize glucose, among many other processes." The brain - also an organ - changes, too, Dr. Varner says, but there's little functional difference for most people. Most of the effects of aging on the brain, producing mild cortical atrophy, are minimal. Researchers now know that the human brain is extremely flexible and continues growing, generating new cells and connections among cells, well into adulthood. But as people age past 65, the changes become more evident and that, coupled with the fact that more people are living longer, makes the issues of aging crucial in our society. "If people reach 65, statistics show that more than likely they can count on an average of an additional 17.5 years of life - about 12 of them with full function," Dr. Gruber says. "After the age of 65," Dr. Gruber says, "aging does cause changes in the human brain which have mild effects on cognitive functions. There is an overall shrinkage in the size of the brain, a decrease in blood flow, the loss of some nerve cells, changes in the chemical messengers that help the cells communicate, and a deterioration of the nerve cell receptors that the chemical messengers act upon. Usually these changes produce modest changes in a person's visual-spatial abilities, memory, mental flexibility, speed and the ability to perform multiple tasks." However, there is a population over 65 who are affected by changes in the brain, coupled with normal aging, that can cause or complicate psychiatric disorders, such as dementia, depression, anxiety disorders, bipolar disorder or schizophrenia. (Major depression affects about 2 percent of the elderly population; minor depression, 10 percent; bipolar disorder, formerly called manic-depression, 2 percent; anxiety disorders, 5.5 percent; schizophrenia, .5 percent; substance abuse, 2 percent; other mood disorders, 3 percent; and dementia, 7 percent.) It is this population of elderly with acute and chronic psychiatric disorders that Drs. Gruber, Varner and Lesser treat at HCPC and MSI and who were part of their attempt to learn more about the relationship between aging, human intellect and psychiatric illness. "The clock drawing test (CDT) has been used for decades with the general population as a neuropsychological screening test," says Dr. Gruber. "But there is renewed interest in it as physicians search for a simple, quick and reliable screening tool to assess cognitive impairment or dementia in the elderly. "By looking at the way a person draws a clock face," Dr. Gruber says, "you learn about their perceptual process, visual and spatial abilities, drawing abilities, attention to left and right, memory, "executive skills" (planning, organizing, sequencing), and other neuropsychological capacities," he says. "And some researchers have shown that particular nervous system deficits (e.g., a stroke in a certain area of the brain) are associated with certain kinds of deficits in the way a clock was drawn."
The CDT is simply that: a person is given a sheet of paper and asked to draw the face of a traditional (analog) clock with a certain time, such as 11:10 (ten minutes after 11 o'clock). There are actually two tests. You can either have people draw the clock from scratch on a blank piece of paper or give them a paper with a pre-drawn circle; depending upon this initial set-up, each test can provide different information. For example, given a blank piece of paper, a person may make a nice round circle in the middle of the page, or he may make no circle, or his circle might be at the edge of the page or lopsided. All these tell you certain things about his abilities with regard to organization, planning and proportions.
©2006 Texas Medical Center E-Mail: tmcinfo@texmedctr.tmc.edu URL: http://www.tmc.edu/tmcnews/07_01_00/page_08.html |
